Compositions for electrosensitive recording material

ABSTRACT

Compositions for electrosensitive recording material used as recording paper for facsimiles etc., comprise zinc oxide doped with trivalent or tetravalent metal elements and a binder.

United States Patent 151 3,691,105 Juna et a1. 1451 Sept. 12, 1972 41COMPOSITIONS FOR [58] Field of Search ..96/l.5, 1.1 1.3; 252/501,

ELECTROSENSITIVE RECORDING MATERIAL Inventors: Kiyoshi Juna; NoboruShinada; Masuo Tsuchiya, all .of Research Laboratory, Kansai Paint Co.,Ltd., 1200, Yawata, Kanagawa-ken, Japan Filed: Oct. 21, 1910 Appl. No.:82,855

Foreign Application Priority Data May 12, 1970 Japan ..45/39691 June 29,1970 Japan ..45/55947 Aug. 28, 1970 Japan ..45/74947 US. Cl. ..252/519,117/201, 117/221,

' 252/520, 252/521 Int. Cl. .1 ..l-I0lb l/08 [5 6] References CitedUNITED STATES PATENTS 3,138,547 6/1964 Clark ..117/201 X 3,411,94811/1968 Reis ..204/2 X 3,547,627 12/1970 Amidon et a1. ..96/ 1.5 X2,887,632 5/1959 Dalton ..204/2 X 3,212,890 10/1965 Kimble et a1 ..96/1.8 X 3,128,204 4/1964 Schaum et a1. ..117/221 Primary Examiner-RobertF. Burnett Assistant Examiner-Joseph C. Gil Attorney-Ostrolenk, Faber,Gerb & Soffen [57] ABSTRACT Compositions for electrosensitive recordingmaterial used as recording paper for facsimiles etc., comprise zincoxide doped with trivalent or tetravalent metal elements and a binder.

7 Claims, No Drawings COMPOSITIONS FOR ELECOSENSTTIVE RECORDING MATEALThis invention relates to compositions for an electrosensitive recordingmaterial and more particularly to electrosensitive recording materialcomprising binder and zinc oxide doped with a doner impurity elementand, if necessary, metallic soap of fatty acid.

It is known to us compositions to which electric conductivity has beenbestowed by adding a conductive material as electrosensitive recordingmaterials. Metals, carbon black or graphite, or electrolytes such asmetal chlorides, have been used as such additives. However, these havenumerous defects such as being economically disadvantageous when a metalis used; a recording which has sufficient contrast cannot be obtainedbecause the coated film is colored grey when carbon black or graphite isused; and the base material of the electrosensitive recording materialis eroded when electrolytes such as metal chlorides are used.

Furthermore, the previous electrosensitive recording material had thedefect of requiring a higher voltage, for example from to volts, inorder to obtain a recording which has sufficient contrast. The object ofthis invention is to eliminate such defects and provide compositions forelectrosensitive recording materials which can respond to recordingsignals at a lower voltage and faster than the previous electrosensitiverecording material, and also by a dry method.

This invention relates to the compositions of electrosensitive recordingmaterial whose chief components are zinc oxide doped with a donorimpurity element and a binder, and, if necessary, a metallic soap offatty acid.

The impurity metal is doped to zinc oxide and made semiconductive.Metals used for this invention are elements which have a higher valencethan the valence of zinc the form of zinc oxide and generally, these aretrivalent or tetravalent metallic elements and are doped to zinc oxideby heat energy. Elements which are to be doped to zinc oxide must haveionic radius which is smaller than the ionic radius of zinc (0.74A).Calcining with a higher temperature for a longer time is necessary fordoping an element having larger ionic radius than that of zinc, andsintering takes place during calcination. Therefore, it is moredifficult to pulverize the resulting material as compared with usingzinc oxide doped with donor element having smaller ionic radius than theionic radius of zinc in this invention. As a result, such materials arenot suitable as compositions of this invention. Metallic ions whichsatisfy such condition are trivalent metallic ions such as Co (ionicradius 0.65A,), Ga (0.62A), Al (0.50A), Fe (0.60A) and Cr (0.64A), andtetravalent metallic ions such as Si (0.41A), Ge(0.53A), Ti (0.68A) andSn (0.71A), and normally, it is preferable to use transition elements.The quantity to be doped to zinc oxide is a range of from 0.005 to 10.0percent by mole.

It will be difficult for the zinc oxide to attain the objects of thisinvention if the quantity is smaller than 0.005 percent by mole orlarger than 10.0 percent by mole.

In manufacturing zinc oxide doped with a donor impurity metal, thespecified quantity of zinc oxide and compound of element having an ionicradius smaller than the ionic radius of zinc are mixed and blended,

I resin,

calcined at a temperature of 800l,400 C in air and then pulverized. Inthe case of a calcining temperature lower than 800 C, a zinc oxide dopedwith a donor element which is suitable for this invention will not beobtained; it will not conductive. On the other hand, when the calciningtemperature is higher than l,400 C, it is difficult to crush the zincoxide particles doped with donor element and it will be difficult to useit as fine powder such as in this invention.

The semiconductive zinc oxide obtained in this invention is dispersedinto the binder in a range of from 150 to 1,000 per hundred resin(hereinafter referred in simply as Pl-IR), preferably from 250 to 800PHR. When the addition and dispersion concentration is less than 150PHR, the hiding power of the compositions becomes very low. When theconcentration is more than 100 PHR, the dry film obtained from coatingsaid compositions is markedly brittle and has lower adhesive property.

'It is not necessary to use special resin as binder in this inventionbecause it is possible to use the general resins which have been used asvehicle for paints. For example, the binder may be one or more resinsselected from urea resin (urea-alkyd resin), alkyd resin (oil-free,modified drying 'oil or modified semi-drying oil), melamine resin(melamine-alkyd resin), polyurethane vinyl resin (vinyl chloride-vinylacetate copolymer), epoxy resin, nitrocellulose lacquer, acryl lacquerand acryl resin.

A suitable resin selected from the binders abovementioned is dissolvedin a suitable organic solvent or mixture thereof to obtain the resinsolution, the semiconductive zinc oxide in dispersed into the resinsolution with a pebble mill or sand grinder, and then a suitable organicsolvent is added for diluting to a viscosity which is suitable forcoating on the base material.

It is not necessary to use a special organic solvent in this inventionbecause it is possible to use the general solvent which have been usedas solvents in the paint industry. If necessary, metallic soaps of fattyacids may be added.

Since smooth and flat coated film is obtained by using a metallic soapof fatty acid in the compositions according to this invention, arecording having favorable contrast is obtained easily, and it is notnecessary to apply high voltage. As a result, in this invention, thefilm is prevented from break due to electric current and due to electricdischarge. Furthermore, the soap improves the adhesive property of thefilm on the base material by its plasticizer-like action on the film andalso improves flexibility. Soaps of fatty acids which can be usedindependently or as mixture are aluminum, copper, zinc, lead, iron,magnesium, cobalt, barium, nickel and lithium salts of palrnitic acid,oleic acid, stearic acid, lauric acid and caprylic acid. The quantity ofsaid soap used is a range of from 5 to PHR, preferably from 10 to 60PHR. When the quantity is smaller than 5 PER, it is necessary to applyhigh voltage, and the dry film obtained is rough and has poorflexibility. On the other hand, when the quantity is larger than 80Pl-lR, it is also necessary to apply high voltage, and the adhesion ofthe dry film obtained is poor.

EXAMPLE 1 500 g of zinc oxide doped with aluminum (1.0 mole as aluminumoxide), 40 g of Versamid No. 100 (polyamide resin manufactured byGeneral Mills C0.), 150 g of isopropyl alcohol and 150 g of toluene werecharged into a pebble mill and dispersed for 20 hours. Then the mixturewas removed from the ball mill, and 60 g of Epon No. 1004 (epoxy resinmanufactured by Shell Chemical Co.) and 40 g of methyl ethyl ketone weremixed to prepare the composition. This composition was coated with a barcoater to a dry film thickness of about 10 microns on a conductivematerial laminated and vapor-deposited with tin. In two cases, 8 voltswere applied while moving said coated material, and a mark havingfavorable contrast was obtained.

EXAMPLE2-9 Materials with compositions indicated in the following tablewere coated in a similar manner as in Example 1 on a conductive materiallaminated with aluminum. Each 500 g of zinc oxide was doped with each ofthe following donor impurities.

Recordings were obtained from compositions obtained by altering thequantity of semiconductive zinc oxide in Example 1 from 500 g to variousquantities. Otherwise the kind and quantity of other materials and themanufacturing process exactly the same. The quantities used areindicated below.

Example Semiconductive No. Zinc Oxide (PHR) Voltage (V) EXAMPLE 11 500 gof zinc oxide doped with iron (0.8 mole as iron oxide), 70 g of Epon No.1007 and 50 g of methyl ethyl ketone were charged into a pebble mill anddispersed for hours. Then the mixture was removed from the ball mill;and 30 g of Versamid No. 100, 150 g of isopropyl alcohol and 150 g oftoluene were added to prepare the composition.

This composition was coated with a bar coater to a dry film thickness ofabout 10 microns a conductive material laminated with aluminum. 8 voltswere applied while moving said coated material and a mark havingfavorable contrast was obtained.

EXAMPLE 12- 19 Materials with compositions indicated below were coatedin a similar manner as in Example 1 1 a conductive material laminatedwith zinc.

Example Binder Composition (solid) Voltage 12 Beckosol J-557 (Note I)100 g Co 0.03 g 8.5

Dryer Pb 0.3 g

13 Beckolite M-6402-50 (Note 2) 80 g 8.0

Super Beckamine TD-126 (Note 3) 20 g 14 Beckurol 6-1850 (Note 4) 45 gBeckosol J-579 (Note 5) 55 g 8.0 Para-toluenesulfonic acid 2 g 15Beckosol 1323 (Note 6) g 9.0

Super Beckamine .l-820 (Note 7) 30 g 16 Hitaloid 2405 (Note 8) g 8.5

Melan 20 (Note 9) 20 g 17 Beckosol J-544 (Note 1) 50 g V4 Nitrocellulose(Note 10) 40 g 8.0 D.O.P. 10 g 18 Lustrasol A-ll l-SO (Note 11) 65 gCellulose acetate butylate 20 g 8.0 D.0.P. 15 g 19 VYHH (Note 12) 42 gVMCH (Note 13) 42 g 8.5

D.O.P.15 g Stabilizer (Note 14) l g (Note 1) Trade name of safflower oilmodified alkyd resin manufactured by Japan Reichhold Co.

(Note 2) Trade name of oil free alkyd resin manufactured by JapanReichhold Co.

(Note 3) Trade name of butylated benzoguanamine resin manufactured byJapan Reichhold Co.

(Note 4) Trade name of butylated urea manufactured by Japan ReichholdCo.

(Note 5) Trade name of tall oil modified alkyd resin manufactured byJapan Reichhold Co.

(Note 6) Trade name of coconut oil modified alkyd resin manufactured byJapan Reichhold Co.

(Note 7) Trade name of butylated melamine resin manufactured by JapanReichhold Co.

(Note 8) Trade name of thermosetu'ng acrylic resin manufactured byHitachi Chemical Co., Japan.

(Note 9) Trade name of butylated melamine resin manufactured by HitachiChemical Co. Japan.

(Note 10) Nitrogen content= 11.7 12.2 percent. (Note 11) Trade name ofpolyacryl polyol manufactured by Japan Reichhold Co.

(Note 12) Trade name of vinylchloride-vinylacetate copolymermanufactured by U.C.C.

(Note 13) Trade name of vinylchloride-vinylacetatemaleic acid copolymermanufactured by U.C.C.

(Note 14) Used mercaptodibutyltin maleate.

EXAMPLE 20 500 g of zinc oxide doped with titanium (0.05 mole as TiO gof Lustrasol A-809 (Acryl resin manufactured by Japan Reichhold C0.), gof butyl acetate and 70 g of toluene were charged into a pebble mill anddispersed for 20 hours, 10 g of aluminum oleate was added and mixed for1 hour more, then the mixture was removed from the ball mill and aquantity of polyisocyanate, for example XDI (xylene diisocyanate) whichis equivalent to the hydroxyl value of Lustrasol A-809 was added toprepare the composition.

This composition was coated with a bar coater to a dry film thickness ofabout 10 microns on a conductive material laminated with aluminum. 6.5volts was applied while moving said coated material, and a mark havingfavorable contrast was obtained.

EXAMPLE 21 A composition was prepared by the same procedure as Exampleusing 40 g of zinc stearate in place of aluminum oleate as the metalsoap of fatty acid and 5 volts was applied through the film formed onthe aluminum layer by the same method. A record having favorablecontrast was obtained.

EXAMPLE 22 A composition was prepared by the same procedure as Example20 using 60 g of copper palrnitate in place of aluminum oleate as themetal soap of fatty acid and 6 volts was applied through the film formedon the aluminum layer by the same method. A record having favorablecontrast was obtained.

What is claimed is:

l. A composition for an electrosensitive recording material, whichcomprises zinc oxide doped with an oxide of a donor impurity metalhaving an ionic radius of less than 0.74 Angstrom units and selectedfrom the trivalent or tetravalent metals, the zinc oxide doped componentbeing dispersed in a binder in an amount from 150 to 1,000 parts byweight of the zinc oxide doped component per 100 parts by weight of thebinder.

2. The composition of claim 1 wherein the donor impurity metal is atrivalent metal selected from the group consisting of cobalt, gallium,aluminum, mercury, iron and chromium, and in which the zinc oxide isdoped with the oxide of such metal in an amount of from 0.005 to 10.0molar percent thereof.

3. The composition of claim 1 wherein the donor impurity metal is atetravalent metal selected from the group consisting of silicon,germanium, titanium and tin, and in which the zinc oxide is doped withthe oxide of such metal in an amount of from 0.005 to 10.0 molar percentthereof.

4. The composition of claim 1 further including as a plasticizer for thecomposition a metallic soap of a fatty acid having eight to 18 carbonatoms, in an amount of from 5 to parts by weight per parts of the binderfor the composition.

5. The composition of claim 4 wherein the donor impurity is a trivalentmetal selected from the group consisting of cobalt, gallium, aluminum,mercury, iron and chromium, and in which the zinc oxide is doped withthe oxide of such metal in an amount of from 0.005 to 10.0 molar percentthereof.

6. The composition of claim 4 wherein the donor impurity metal is atetravalent metal selected from the group consisting of silicon,germanium, titanium and tin, and in which the zinc oxide is doped withthe oxide of such metal in an amount of from 0.005 to 10.0 molar percentthereof.

7. The composition of claim 4 wherein the metallic soap is an aluminum,copper, zinc, lead, iron, magnesium, cobalt, barium, nickel or lithiumsalt of a fatty acid selected from palmitic acid, oleic acid, stearicacid, lauric acid and caprylic acid.

2. The composition of claim 1 wherein the donor impurity metal is atrivalent metal selected from the group consisting of cobalt, gallium,aluminum, mercury, iron and chromium, and in which the zinc oxide isdoped with the oxide of such metal in an amount of from 0.005 to 10.0molar percent thereof.
 3. The composition of claim 1 wherein the donorimpurity metal is a tetravalent metal selected from the group consistingof silicon, germanium, titanium and tin, and in which the zinc oxide isdoped with the oxide of such metal in an amount of from 0.005 to 10.0molar percent thereof.
 4. The composition of claim 1 further includingas a plasticizer for the composition a metallic soap of a fatty acidhaving eight to 18 carbon atoms, in an amount of from 5 to 80 parts byweight per 100 parts of the binder for the composition.
 5. Thecomposition of claim 4 wherein the donor impurity is a trivalent metalselected from the group consisting of cobalt, gallium, aluminum,mercury, iron and chromium, and in which the zinc oxide is doped withthe oxide of such metal in an amount of from 0.005 to 10.0 molar percentthereof.
 6. The composition of claim 4 wherein the donor impurity metalis a tetravalent metal selected from the group consisting of silicon,germanium, titanium and tin, and in which the zinc oxide is doped withthe oxide of such metal in an amount of from 0.005 to 10.0 molar percentthereof.
 7. The composition of claim 4 wherein the metallic soap is analuminum, copper, zinc, lead, iron, magnesium, cobalt, barium, nickel orlithium salt of a fatty acid selected from palmitic acid, oleic acid,stearic acid, lauric acid and caprylic acid.